Field
The present disclosure relates generally to methods and apparatus for conformal shielding, and more specifically to conformal shielding utilizing a removable stencil and shielding walls embedded within the stencil to more efficiently engender shielding for surface mounted circuit devices on a printed circuit board.
Background
An electrical device, such as a computing or communication device, typically includes a printed circuit board (PCB) having various circuit components to enable the functionality of the electrical device. Such circuit components may be referred to as an integrated circuit, chip, or microchip, and may be mounted on the surface of a PCB. These chips may be referred to as surface mount technology (SMT) components. In cases where all components of a computer or other electronic system, such as a wireless phone, are integrated into a single chip, the single chip may be referred to as a system on a chip (SoC).
Various circuit components in devices, such as wireless devices, may generate electromagnetic interference (EMI), or may be sensitive to EMI from other components or from EMI originating outside of the device. Accordingly, these circuit components may need to be shielded to either contain generated EMI or protect against outside EMI. Due to the constant demand to make electrical devices smaller, however, there is a desire to reduce the area and thickness of chips within these devices.
In some solutions, conformal shielding is utilized to address the above concerns. Conformal shielding for wireless devices has many advantages, including better shielding efficacy, minimization of device height, and help with heat conduction. Currently, there are two conventional conformal shielding approaches. In the first approach, a metal frame acting as a shielding wall is applied to the PCB when the SMT components are mounted. This approach typically requires a relatively large surface area on the PCB to allow the metal frame to be mounted due to large tolerances in the placement accuracy of the metal frame and SMT. After mounting of the metal frame, a laser may then be used to expose the metal frame so that metallic paint can be subsequently applied to the mold to complete the shielding compartments. In a second conformal shielding approach, a laser is used to etch or scribe the molding material to form trenches. A conductive gel material is then applied into the trenches to form the shielding walls, and finally metallic paint is applied to the mold to achieve the shielding. Both processes are time consuming and involve many processes of repeated cleanings and baking and drying.
Thus, improvements in conformal shielding are desired.